Half and Half
by thewillofpos
Summary: Percy had just finished a second war. Hoping to return to a normal life which involved school and heading to college in New Rome. However, another war was in his midst but not from his world. Angels and Demons were always seen as myth to him. But he is proven wrong when a group of Shadowhunters find him are intrigued by his power and swordsmanship. AU Some Swearing. ON HIATUS
1. Chapter 1

**Half and Half**

**Disclaimer: I do not own The Mortal Instruments or PJO**

**Chapter 1: **

The night is a frightful thing. The most evil and sinister beings tend to stir and lurk in the shadows under the cover of darkness. The absence of light appeals to those with the evil intent of doing harm. For the Shadowhunters it was a recurring and daily fact of life. Even so, they tended to do their travel under the cover of darkness even with the threat of demons.

Percy was taking the local bus in Manhattan to go back home to his mother. She knew not to worry about him if he didn't show up, either side tracked by fighting for his life from monsters or Camp Half-Blood requiring of his services. But today was definitely a different night unlike the rest.

He was awaiting at the bus stop after a whole day of school and attending after school tutoring. The night sky was darker than usual which didn't seem to bother Percy as he maintained the nodding of his head with music blasting from his headphones.

Riptide or Anaklusmos was within reach inside a pocket within his jacket. It was uncharacteristically chilly this particular night as Percy could see the water vapor come out of his nose and mouth from the chilly and windy night.

He was situated near an alleyway, the darkness not fazing him as he was veteran of war within his own right. As he checked his wrist watch he noticed the bus was running late. Which didn't bother him all too much as he kept his head bobbing along with the music.

However, a young little girl passed him, almost as if under hypnosis not bothering to acknowledge the teenage boy waiting for the bus.

The young girl went into the dark alleyway which Percy found odd. Percy was caring and curious at the time. He held the sense of responsibility to make sure the little girl was not another amber alert, or worse another loss of life at such a young age.

Disregarding the arrival of his bus, he decided to follow the girl through the dark and smelly alleyway. The girl walked and walked under her trance until she made her way across another alleyway.

After following the girl for a few minutes, the girl broke her walk into a full fledge sprint. Percy ran after her, hoping he wasn't the reason she began running. She ran through another corner, and when Percy turned the corner, he realized he lost the girl. He turned around in a full circle looking for any hiding spots. The girl was nowhere to be seen which only further worried him.

It didn't take long for Percy to turn his attention to the loud and screeching scream that was heard further down the alleyway. Percy hoping, he could reach in her time began sprinting not worrying about getting lost in the shady part of the city.

He found the girl being surrounded by four hooded individuals with blades drawn with an unusual feint white light, he realized this was no ordinary encounter.

"What the hell are you doing?" Percy screamed as the hooded figures turned their attention to him.

"He's not mundane. He can see our weapons." A feminine voice spoke out alerting her group members.

Percy looked at the group almost a little intimidated. They looked like some cult that would sacrifice children to their radical ideals. That wasn't going to happen under his watch.

"I suggest you let the girl go." Percy said as he neared the girl slowly.

"I suggest you remove yourself. Before you get hurt." This time a male voice with charisma responded.

"I can't. You'll have to go through me." Percy said as he fetched Anaklusmos in its pen form.

When he got the pen out of his pocket the dark hooded figures couldn't help but laugh at the absurdity of the black haired teen's antics.

"You can't be serious. You're going to fight us with a pen? Pathetic." The male voice said as he began approaching Percy and the little girl.

Percy uncapped Riptide as it sprung to a three and half foot-long leaf shaped sword. With its own gold feint light of its own. The lone hooded figure stopped in his tracks as he now saw Percy wasn't playing along after all.

"Where did you get that? I've never seen it before." This time a different feminine voice responded.

"None of your business. Now are you going to let the girl go or not? That way we can get this over with." Percy responded.

The girl meanwhile watched unflinchingly at the argument going on with the Shadowhunters and the lone demigod. A sinister smile was plastered on the young girl's face.

"Move aside." The male that had walked up to Percy said.

"No." Percy said as he began closing the gap between the two.

"Jace don't. You're going to hurt him." Both the females of the group said in unison.

The one known as Jace closed the gap between himself and Percy with inhuman speed. Jace thrusted his sword toward Percy's midsection which Percy hastily blocked with Riptide. To the normal eye the fighting was a blur as the seraph blade and bronze Xiphos clashed between each other. Each parry between the two combatants caused sparks.

The _little girl _as Percy had called it began screeching a deafening scream as both Percy and Jace turned their attention. The demon ripped its host's body as it revealed its true form. The features were not distinguishable as the demon was pure darkness and the face of a hideous monster with red eyes.

"What the hell is that?" Percy said as he backed up.

"It wasn't a little girl as you said. It's a demon and we're known as Shadowhunters." The red-haired girl said as she dropped her hood and revealed her face.

"So, a monster?" Percy replied as he joined the group, albeit a little cautiously.

"A demon. They originate from the void." Jace said as he dropped his hood to reveal a handsome face, blonde hair, gold eyes, and a muscular physique.

"Okay… Well I don't know about you guys, but I'm not trying to die today, so let's hurry up and kill this thing." The entire group of Shadowhunters nodded and began staring the demon down.

Unlike the Shadowhunters, who were busily trying to figure the best point of attack to defeat the demon, Percy decided to use his own powers. He concentrated as he felt the water around in the atmosphere and felt the familiar tug in his gut. Water began to hastily form as a protective barrier around Percy, following him as he moved. A course of electricity was flowing around the barrier also serving as a shield against anything trying to get into Percy's guard.

"What the?" This time the other female spoke up. As she looked at Percy and the surge of water and electricity coursing around him. She was average height with black hair and brown eyes.

Percy stood his ground as he concentrated on getting more water around him. When he had sufficient water, he used his hands to control the water, and the water mirrored his hands. Two hands made of water appeared and grasped the demon from the midsection and held it in place.

"Now. Attack it!" Percy said and the Shadowhunters obliged as they maneuvered quickly and nimbly and thrusted the demon through the midsection. The demon screeched even louder at the apparent pain and damage the seraph blades seemed to cause.

The demon screeched for a few more seconds before being destroyed.

Percy was a bit tired from the excess use of his power and sat down on the brick covered alley way and the other Shadowhunters watched him as he did so.

Percy for one didn't like to be the center of attention. Even if he was the son of Poseidon, he despised that people saw him as this perfect demigod when he had his own flaws.

"What?" Percy said as he couldn't help the feeling of the awkward tension in the air.

"He has to be a shadow hunter." The red-haired girl said, but not towards Percy but to her group.

"Shadow hunters don't have those kind of powers Clary." Jace said as he began to pace up and down.

"Alec and Izzy, what do you think?' Percy looked at the supposed one that was called Alec. He was shorter than Percy but only by about two inches. He had black hair and the most stunning and clear blue eyes. Just like Jace, he had a radiant handsomeness. Izzy was the other female that had been confused and shocked at Percy's power.

"Only Warlocks have that form of magical ability. But he doesn't have that kind of distinguishing physical features that warlocks have. He appears human and mundane." Alec said as he looked at Jace who stopped pacing.

"There's only one way to find out." Clary the red-headed girl began approaching Percy with a twig in her hand, that appeared to have an aura.

"What are you doing? And what is that?" Percy said as he began to get up and back up.

Clary held her shadowhunter tool in her hand as she approached Percy. "This is a stele. It's useful for rune making. Now come here I'm trying to heal you." Percy could only frown at the words that were coming out from her mouth.

Percy however, let her come to her and felt her soft and warm hand began rolling up his sleeve and began drawing a symbol on his arm. The 'stele' was kind of hot to the touch went it touched his tan skin. When she had finished, he felt his body refresh and any of his small bruises he had gotten from the fight begin heal.

However, the shadowhunters were amazed at how quickly the rune disappeared almost instantaneously. As soon as Clary had finished creating the _Iratze _on Percy it was absorbed within two seconds.

"We have to take him to the institute." Clary finally deduced as she looked at the group.

"Uh no thanks. I do not want to go to the institute as you call it, sounds like an asylum for crazy people." Percy said as he began rolling his sleeve down.

The group looked at Percy wondering if they should heed to Clary's advice. As they were conjuring their decision, drops of rain began to fall and Percy felt more energized as the water was rejuvenating his strength.

"Fine. We'll take him. But just to figure out who is, and if he truly is a shadowhunter." Jace said as he pulled his hood over his head and began walking back the distance to the New York Institute.

Izzy, Alec, and Clary followed. Percy was having an internal conflict on whether he should follow them. He looked at the shadowhunters and in the other direction which would be to his apartment. But in the end, he decided he wanted to know more about the 'shadowhunters' and if they would be valuable allies to him…

**Authors Note: So, this was a concept I was thinking of for some time. I don't know if it will receive any views or even follows. But it was something fun to write. It's just two worlds clashing and if it receives some good feedback, I can even continue the story's storyline and Percy's relationship with the mysteriousness of the shadowhunters. **

**I'm obviously going to include Annabeth if the story continues. I want the pairing to stay cannon to Percy's world. But this will most likely stay within the Shadowhunter world just because I want Percy to experience and learn about their world. Only Annabeth will be his companion from the Greek world If I continue this story. Fight scenes and actions are going to happen, it's just a matter of setting them up. Some might even believe Percy could be a danger to the shadowhunters and might want to dispatch him, but you'll have to find it. Or he could possibly be someone with power within the institute. Only I know**


	2. Chapter 2

**Half and Half**

**Disclaimer: I do not own The Mortal Instruments or PJO**

**Chapter 2: **

Percy was still wary at the prospects that the four hooded individuals could decide that he was a threat to them and end his life at the moment as they walked through the rainy New York night. Although he knew that Annabeth would flip New York upside down just to find him. He didn't know which option was the scariest, getting killed by these mysterious teenagers or feel Annabeth's wrath in the afterlife.

"We're here." Jace said.

Percy looked at where exactly 'here' meant and realized it looked like an abandoned church to the visible eye. But as he neared the church, it began unraveling almost mist like as it began to look like a well maintained and beautiful church. He noticed the four individuals looking at him hesitantly asking themselves how they should proceed.

"Well let's go inside. But you'll open the door." Jace pointed to Percy who was more confused than ever.

"I don't have a key to get in." Percy replied.

"If you're shadow hunter you don't need a key or password. Just push the door open." Clary replied as they led him to the door.

As Percy stepped up to the door the others looked at him expectantly. When he pushed the door open their presumed assumption, they believed, were proven correct. Or could it possibly be the divine blood bestowed onto him by his divine Greek father.

The group members hastily made their way inside brushing past Percy not checking to see if he followed behind them. Percy after a few seconds began pondering whether he should follow, and decided to proceed and enter the building while closing the door.

The inside of the church looked as expected. The pews where worshippers sat and responded to the well-orchestrated messages were neatly arranged facing the altar. The light within the church was white but not overly harsh as the witch light provided sufficient light without blinding the casual user.

The group made their way to a different doorway and proceeded to go through it. Percy as he followed realized there were endless corridors and hallways. Without the assistance of the Shadowhunters he would've gotten lost on his own.

"To the library" Jace commanded as he directed the rest of his comrades to a double arched door.

As they spilled into the library Percy could only marvel at the circular room filled with endless bookcases and books. Which brought the thought of Annabeth who was in love with reading.

"Oh my" Percy said in realization as he was supposed to Iris message Annabeth as soon as he got home.

"This is just the New York Institute the ones in Alicante hold much more books than this." Alec said as he sat down in a nearby chair." Percy however wasn't marveling at the books but that he had to Iris message Annabeth.

Percy fidgeted through his pocket as he looked for drachmas. The only things he managed to find were pens, pencils, crumpled up papers and some bubble gum wrappings in his pocket.

"Of course" Percy broke the silence as the shadow hunters looked in confusion at Percy's odd behavior.

Percy continued to look through his jacket pocket until he finally found a golden drachma in one of his hidden pockets.

"Finally." Percy said as he looked at the group of shadow hunters.

"What is that? Why do you even need it?" Jace asked.

When Jace had seen the teen interrupt their talks with the demon he could only marvel at the utter stupidity Percy showed. Perhaps it was his ignorance of being lost in the mundane world and the lack of shadow hunter training that made him seem dense. Obviously, he had gotten lucky in terms of the short sparring session they had before the demon had decided to attack. That or he was insanely gifted with perhaps even better reflexes than his own.

"I need this to contact my girlfriend." Everyone looked baffled at the oddity of Percy in general. They were starting to grow wary that maybe they had found a crazed shadow hunter.

"You guys have like a fountain or somewhere misty around here?" Percy looked at Clary as she seemed the friendliest.

"Well not just laying around, why?" She pried as the handsome boy kept murmuring to himself.

"I'll show you." Percy replied to Clary.

Clary knew there was no fountain within the institute, so she took Percy to the bathroom and proceeded to turn the hot water on as the humidity began to sprout water vapor.

"We need the sink to be full of water so I can flip the drachma in." Clary followed Percy's instructions as he covered the filter so the water wouldn't escape.

"Now we need a rainbow. You wouldn't happen to have any rainbow bath bombs, would you?" Clary's cheeks turned a tint of red for a second before she scoured through the sink vanity and found the rainbow bath bomb.

Percy unwrapped the bath bomb and dropped the bath bomb into the sink of the bathroom. As the rainbow colors began to bleed out of the bomb Percy flipped the drachma.

"Oh Iris, goddess of the rainbow, please accept my offerings. Show me Annabeth Chase" Percy concluded as a blob of mist showed a blonde girl fidgeting and pacing around a small yet cozy apartment.

"Annabeth." Percy broke the girl's pacing as she turned to look at the Iris message.

"Percy, thank the heavens you're safe. Where are you? I tried to Iris message you, but it was being blocked for some odd reason. And who is your friend?" Annabeth spoke with a clear voice through the supernatural messaging system.

Clary on the other hand had thought that she had seen anything and everything supernatural ever since she had discovered she was a shadow hunter. However, communicating through a rainbow and mist seemed to shatter all previous judgements on inexplicable things she believed to know. Not only that but the sheer fact it was possible through simple means impressed her even more.

"Oh, this is Clary." Percy looked at Clary before looking back to his girlfriend.

"What are you guys doing in the bathroom?" She pried although containing her jealous tone.

"Oh, we were just finding a way to contact you. Clary helped me. In order to explain everything, I think you should meet me here." Percy continued as he looked at Annabeth who simply nodded and grasped her bag over her shoulder.

"Give me the address." Annabeth asked more so to Clary than to Percy.

As the girls exchanged information Percy could only contemplate on the vastness of other worlds involved within his own. Shadowhunters seemed to be a small discovery to himself in addition to the other pantheons of gods. Which made him think that if Shadowhunters existed to keep the world safe from demons that meant that they were perhaps hunted down just like demigods by their demons.

"Okay Percy I'll be there as soon as I can. I already sent a message to Camp Jupiter and Camp Half Blood that I found you. We cannot have another one of your disappearances." Annabeth sternly advised him as Percy began to feel embarrassed.

Before Percy could reply Annabeth obstructed the communication and the mist vanished as the two teenagers stood in the bathroom awkwardly. Percy looked at Clary and then proceeded to shrug his shoulders and signal her to lead the way.

They made their way towards the spherical library once again as they noticed the other three shadowhunters had begun to go through books within their archives. Percy being dyslexic decided that he would sit at one of the empty wooded and old tables to wait for Annabeth.

About an hour later she had simply opened the Institutes doors and proceeded to navigate through the endless and winding corridors with no issue to the surprise of the Shadowhunters as the blonde knocked on the library door. Clary opened the door with a shocked expression on her face as Jace, Izzy, and Alec began to unsheathe their seraph blades.

"Hold up. She's okay she's my girlfriend." Percy interceded as he quickly got up and in between the shadowhunters and Annabeth.

"How the hell did she navigate through the Institute. I was practically born in here and sometimes I take the wrong turn." Alec responded a little surprised.

"Simple architecture. I can process it through my brain, it's almost as if I can see the blueprints through my own eyes. Plus, I've studied on religious buildings of all kinds, temples, synagogues, churches, and mosques. Funny that they're very similar in a way." Annabeth responded with a shine in her eyes.

"What the actual hell is going on here?" Jace finally spoke as he looked at the two demigods with a hint of judgmental eyes and envy.

"You have the ability to control water and bend it to your will." Jace pointed towards Percy.

"And you have a supernatural intelligence, with the ability to see layout of buildings." Jace continued as he picked up his book and tried to read what was within.

Jace continued to read and sighed in defeat unable to find any useful information on humans or mundanes having the capability to bend water to their will or see blueprints by simply looking at a structure. In all honesty, he was beginning to feel fear within himself, for all he knew they could've been offspring of demons.

"We're demigods. Direct children of gods and mortals." Annabeth broke the silence as she looked at Jace with unwavering eyes.

The shadowhunters kept their dignity as their mouths had the ability to stay closed, if not their jaws would've dropped to the floor if it would've been humanely possible. As they contemplated Annabeth's words, she decided to enlighten them on their inability to believe that other specific powerful people still existed outside the shadowhunter world.

"Perhaps you've heard of the Greek myths. The twelve major Olympians. Even in ancient stories, there have been accounts and tales of gods descending the heavens or wherever they linger to satisfy their lustful desires with mortals. We are the consequences of that." Annabeth explained as the room continued to be silent.

"I can process information quicker; I can process structures or anything that has remotely any logic to it and piece it together with just my mind. I'm very handy with basically any weapon and I'm one of the best battle strategists to ever live. I was able to gain these abilities and have a particular knack and strengths in these areas because my mother is Athena the most intelligent and wise goddess of the twelve Olympians." Annabeth boasted with pride as she continued to drop bombshell after bombshell on the shadowhunters.

"So, they exist. The Greek gods, they weren't actually myths they are indeed real?" Alec found it to be a tough pill to swallow.

"Yes, they do. Some of them have faded due to lack of respect and worship but for the most part they exist." Annabeth replied.

"And Percy is the son of Poseidon, one of the three eldest gods. Poseidon is the god of the seas and that is why Percy has the ability to control water." Percy could only smile awkwardly as the attention was focused on him.

"This must be something of extreme rarity than. So, it is only you and Percy in existence." Jace asked.

Annabeth could only scoff. The gods continued to have children like it was their duty to do so. "Well there are few hundred of demigods lingering around the world. However, that number could be greater if many didn't perish at the hands of monsters." Annabeth trailed as she remembered how she had lost many of her friends in both wars waged against Olympus.

"We must take this to the Clave." Alec told Jace as Jace's golden eyes were dark with thoughts.

"No, we can't. They're paranoid, we don't want them to stray away from the true enemy which is Johnathan." Jace turned down Alec's proposal.

"We already have a war to worry about, we can't focus on other things. If we do, we will be crushed by Jonathan, the endarkened, demons, and the faeires." Jace said as he looked onto Percy.

"You can help us. If we can get more help on our side, all the better." Jace regretfully asked.

Annabeth and Percy turned pale remembering their past misfortunes in war. The loss of their friends, their unforeseen trip to Tartarus. The horrors of war had done a great toll and trauma to Percy and Annabeth. They didn't know if they could handle another war.

**A/N So… I realized people liked this story more than I realized. I originally wrote just because I was in the mood to write about it. But I guess it's going to be a story. I will continue this. I will involve the two worlds, however, without the involvement of the gods. So I hope you liked this update.**


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